Polymers have broad commercial applications ranging from use in consumer products such as diapers and beverage bottles, to industrial applications such as photoresists, stencils, and films. Typical polymers are made from organic solvent-dependent monomers that undergo polymerization upon irradiation. These often-toxic monomers are recollected in a step that involves an organic wash and therefore requires strict monitoring of waste and solvent evaporation.
Although many polymers are insoluble in water, thymine polymers are generally water-soluble, unless treated. For example, one can cross-link the thymine moieties in the polymer chains to cause the polymer to become insoluble. This cross-linking can be accomplished, for example, by irradiating the polymer at the proper wavelength. The irradiation causes the thymine moieties to undergo a [2+2] photoreaction (a cyclization between two thymine moieties), which connects them to form four-membered rings. The cross-linking causes the polymers to become insoluble and stable to various environmental conditions. The physical characteristics of theses polymers can be controlled by the quantity of the thymine moieties used as co-monomers in the synthesis of the polymer. Once crosslinked, these thymine polymers are fairly resilient.